(1) Field of the Invention
The present invention relates to an industrial robot including an arm pivotally attached to a frame, and a wrist pivotally attached to the arm.
(2) Description of Related Art
A typical industrial robot (hereafter, simply referred to as a “robot”) includes a frame (robot body), an arm pivotally attached to the frame, and a wrist pivotally attached to the arm, to which wrist a working tool (end effector) is attached. A power supply line for supplying power to driving means (a servo motor, for example) for pivoting the arm and the wrist, an air tube for supplying air to an air cylinder provided in the tool, and the like are put together into one bundle (hereafter, the one in this state is referred to as a “cable”), which extends while being accommodated inside the robot or secured to the outside.
The arm and the wrist of the robot are provided so as to be pivotable in a predetermined angle range. If the cable is excessively pulled when the arm and/or the wrist are pivoted, there is a risk of causing damage such as line breakage. For that reason, the cable is installed to extend with a (marginal length) so as not to be damaged even when the arm and/or the wrist maximally pivots. However, if the slack is too long, it may cause resistance against pivoting of the arm and/or the wrist, or may interfere with peripheral members. Moreover, a phenomenon that the cable “moves uncontrollably” may occur when the arm and/or wrist move at a high speed. Further, the outside appearance of the robot becomes degraded.
In order to remove the deficiencies, a large number of patent applications have been filed (see JP-A-2013-49135, for example).